The cost of gun ammunition is such that regular shooters may profitably look at reloading spent cartridge cases, which process may be done at something like a quarter of the cost of purchasing proprietary loaded ammunition. Normal sporting ammunition is Boxer primed with a single center flash hole making the removal of the primer cap an easy task. A removal tool may be fed from inside the empty cartridge case, through the flash hole, to engage the primer cap and force it out using the usual shooter's reloading press and appropriate tooling therein. However, all the world's armies except American, use Berdan primers, with two small, off center flash holes, making it impossible to remove the primer using the normal decapping tooling. Australian military brass employs a Berdan primer, pressed home and roll crimped into place. The removal of the primer cap from this type of cartridge is a difficult exercise.
The most common method of depriming Berdan cartridges has been to dig out the primer with a small chisel. However, difficulties arise in supporting the cartridge case without crushing it whilst the chisel is at work, and avoiding damaging the shoulder around the primer hole in the cartridge whose construction is out of brass and therefore readily damaged. This method can also set back the shoulder in the case thereby creating excessive headspace in the rifle.
Another known technique for removing primer caps from spent Berdan cartridges employs hydraulic pressure. In the simplest form, this technique uses a hand set type of reloader's bullet seating die as a decapper. The fired case is slipped into the body of the die. The base of the case is fitted to the body of the die and an access hole filled with water. The bullet seating stem is quickly placed into the die and given a smart hit with a mallet. The case thus removed is then dried either by heating or by using methylated spirits. However this method of removal has not been useful, being often messy to operate, or slow in operation, such that the process is awkward to employ.
Another known depriming technique employs a Boxer primer on the end of a rod held at the base of the cartridge over the two flash holes. Ignition of the Boxer primer can blow out a Berdan primer.
To date no tooling exists whereby Berdan style ammunition may be quickly and efficiently deprimed for reloading in a manner which is guaranteed not to damage the cartridge case and is simple in its operation.